The present invention relates to the drive system for a thermal printing apparatus and, more particularly, to the drive system of a thermal printing postage meter.
A thermal printing postage meter system, of the type more particularly described in U.S. patent application Ser. No. 07/950,341 (Attorney Docket C-912), is composed of a number of system modules. Generally, upon the placement of an envelope on the deck of the thermal printer by an operator, the envelope is caused to encounter a position sensing assembly that includes an envelope stop arrangement. The envelope stop arrangement prevents the envelope from being longitudinally mis-positioned. Upon proper positioning of the envelope on the deck, the position sensing assembly senses the presence of the envelope and informs a micro controller to first duck the positioning sensing assembly out of the way, inclusive of a stop assembly, by actuating a first motor and initiate the print sequence. The first motor and its associated drive assembly are also responsible for repositioning the platen roller to bias the print area of the envelope into contact with the print ribbon of a ribbon cassette. During the print cycle, the micro controller issues a command to cause a second motor in combination with its associated drive assembly to then drive the platen roller. Rotation of the platen roller causes the envelope and cassette print ribbon to simultaneously traverse the print head while the micro controller concurrently enables the thermal print head. A third motor under the control of the micro controller is provided which acting through the associated drive assembly acts on the take-up spool of the thermal cassette to assure that the thermal ribbon remains tight during the printing process. Following completion of the print cycle, the micro controller causes the first motor and its associated drive assembly to duck the platen roller below the deck and engages the pressure roller for ejection of the envelope by the second motor and its associated drive assembly. The ribbon takeup motor stops. This allows the envelope to advance while the ribbon remains stationary, thus not using ribbon in non-print areas.
It is really appreciated, that the presence of three motors represents a substantial cost consequence to the thermal print system. It shall be further appreciated that the cost consequence is compounded since the thermal printing system must be precisely controlled and, thereby, requiring a precise motor control system and associated motors.